Water enhanced methanol decomposition for simultaneous heat recovery and ready-to-use synthesis gas production over CO2 capture enhanced Ni/zeolite 4A catalyst

Methanol decomposition is considered as a "one stone two birds" approach for simultaneously recovering waste heat and affording synthesis gas. However, this approach requires efficient catalysts with high CO selectivity and low selectivity to byproducts. Herein, a rational design of CO2 capture enhanced Ni/zeolite 4 A catalyst for synthesis gas production by water enhanced methanol decomposition is reported. 5%-Ni/NaA-500 catalyst achieves the YH2 of 80.6%, YCO of 76.2%, H2/CO molar ratio of 2.11, high stability, low selectivity to CO2 and CH4, and no coke at 325 °C. Ni atoms highly disperse on the surface and microporous of zeolite 4 A, and the strong interaction between Ni atoms and zeolite 4 A inhibits the reduction of Ni atoms. Consequently, Ni3+, Ni2+ and Ni0 coexist in 5%-Ni/NaA-500, and the redox couples of Ni3+↔Ni2+, Ni2+↔Ni0, and Ni3+↔Ni0 will enhance the redox processes during methanol decomposition. CO2 capture capacity of x%-Ni/NaA-Y below 350 °C promotes the reverse water gas shift reaction by concentrating CO2 molecules, which hence increases CO selectivity and declines the selectivity to byproducts. The reaction path follows CH3OH→CH3O→CH2O→CHO→CO. This work will pave the way to industrial applications that combine ready-to-use synthesis gas production and heat recovery.